Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Recognise unrepaired and repaired tetralogy physiology, manage cyanotic emergencies and identify late right-ventricular, pulmonary-valve and arrhythmic complications.
Unrepaired tetralogy presents with cyanosis and spells in infancy, but anatomy and prior palliation vary. Adult care must start with the operative history and current anatomy rather than assuming a uniform repair.
Chronic pulmonary regurgitation after transannular-patch repair can be well tolerated for years while the RV progressively enlarges. Timing of pulmonary-valve replacement integrates symptoms, CMR volumes, RV/LV function, exercise capacity and arrhythmia.
Anterior malalignment of the outlet septum during cardiac development creates the ventricular septal defect, overriding aorta and right-ventricular outflow narrowing that define tetralogy.
Chromosomal or single-gene disorders can disturb outflow-tract development. Syndromic features, other congenital anomalies or an affected family history therefore support specialist genetic assessment.
Adults with unrepaired disease or earlier palliative shunts retain variable obstruction and right-to-left flow. Their physiology depends on the native anatomy and every previous procedure.
A transannular patch, pulmonary valvotomy or right-ventricular outflow reconstruction relieves obstruction but may leave important pulmonary regurgitation, often a dominant late adult lesion.
The displaced outlet septum narrows the right-ventricular outflow, leaves a large ventricular communication and positions the aortic root over both ventricles.
Ejection against the narrowed outflow raises right-ventricular pressure and produces hypertrophy. The degree of obstruction, rather than the septal defect alone, largely determines the right-to-left shunt and cyanosis.
The large ventricular defect tends to equalise ventricular systolic pressures, while outflow obstruction diverts part of right-ventricular output through the defect into the overriding aorta. Greater obstruction or lower systemic vascular resistance increases this right-to-left shunt and central cyanosis.
A sudden increase in outflow obstruction or fall in systemic resistance intensifies right-to-left shunting. Pulmonary flow falls, cyanosis deepens and the obstruction murmur may soften.
Chronic pulmonary regurgitation volume-loads and dilates the right ventricle, while operative scar and residual obstruction create substrates for dysfunction and atrial or ventricular arrhythmia.
Central cyanosis, clubbing, RV heave and an ejection systolic murmur from RVOT obstruction; a single S2 may be heard.
Sudden deepening cyanosis, tachypnoea, agitation or syncope from increased right-to-left shunting; the RVOT murmur may soften as flow falls.
Reduced exercise capacity, right-sided dilatation, early diastolic murmur and progressive RV dysfunction.
Palpitations, presyncope or syncope may reflect atrial tachycardia or scar-related monomorphic VT.
Fever, new murmur, embolic signs or abrupt deterioration in a prosthetic conduit/valve needs urgent investigation.
Cyanosis follows longstanding pulmonary vascular disease and reversal of a previously left-to-right shunt. Echocardiography shows high pulmonary pressure without tetralogy’s characteristic outflow anatomy.
Wheeze, crackles or parenchymal abnormalities with no congenital shunt may explain hypoxaemia. A spell with softer outflow murmur and abrupt deepening cyanosis favours cardiac shunting.
Sudden pleuritic pain, new hypoxaemia and acute right-heart strain can mimic congenital deterioration. Comparison with baseline saturation and targeted pulmonary vascular imaging helps discriminate.
In repaired tetralogy, scar-related ventricular tachycardia may cause abrupt palpitations or syncope without a primary fall in oxygen saturation. Rhythm monitoring distinguishes it from a hypercyanotic spell.
Chronic pulmonary regurgitation produces progressive volume overload that may remain silent while the right ventricle enlarges and loses contractile function, potentially leading to systemic venous congestion.
Persistent or recurrent right-ventricular outflow narrowing maintains a pressure load, limiting exercise and accelerating hypertrophy or dysfunction even after an apparently successful childhood repair.
Atrial enlargement, ventricular scar and patch borders permit re-entry. Sustained ventricular tachycardia can cause syncope or sudden death, while atrial tachycardia may worsen haemodynamics.
Residual jets, prosthetic pulmonary valves and conduits provide surfaces for infection or structural degeneration. Fever, a new murmur or abrupt deterioration therefore requires urgent reassessment.
Persistent right-to-left shunting allows venous thrombus or introduced air to bypass the pulmonary filter and enter systemic arteries, risking stroke or other organ infarction.
During a hypercyanotic spell, falling RVOT flow can soften the obstruction murmur as right-to-left shunting increases.
Symptoms can lag behind marked RV enlargement, which is why CMR surveillance matters.
A broadening QRS reflects conduction/scar and often RV dilatation, but risk assessment also needs ventricular function, symptoms and arrhythmia.
An anomalous coronary crossing the RVOT can determine the safety and type of pulmonary intervention.
Air filters on IV lines, meticulous hydration and specialist planning reduce paradoxical embolic and haemostatic complications.
Assuming childhood repair is curative and discharging from ACHD care.
Relying on symptoms alone to time pulmonary-valve replacement.
Treating a hypercyanotic spell as primary lung disease while the murmur becomes quieter.
Using QRS duration alone to decide on an ICD.
Planning RVOT intervention before defining coronary anatomy.
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Which set correctly lists the four core features of tetralogy of Fallot?
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.
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